hello there , i have an Ac motor 220V , 3.5 A , 50 Hz and i want to designed a circuit using 555 , i generate a 100 Hz , + 12 V and a 100 Hz , ( - 12 v ) from two 555 circuit so would it work if i mixed them together ? and would my circuit handel 3.5 A ?
Whats the best simple inverter circuit ?

We very frequently have requests for inverters, but we don't really have one that's viable at this time.

220v @ 3.5 Amperes is 770 Watts. It will also draw up to around 7 times that much power when it's starting up, or around 5,400 Watts. That is not a trivial amount of power.

Let's translate that to inverter requirements. Let's say that you had an inverter circuit that is very good, about 85% efficient. With a 5,400 Watt output requirement, that means you will need 5400/85% = ~6,353 Watts on the input side of the inverter.

Let's say you are powering the inverter from a 12V battery bank. 6,353 Watts / 12v = ~530 Amperes. That is more current than it takes to start up a very large high-compression American V-8 engine.

For your "run" requirement @ 3.5A, that would be ~ 800W / 85% = ~941W in, 941W/12V = 78.4 Amperes current at 12v. That is still a LOT of current, probably about as much as it takes to start a 4-cylinder automobile engine. You would need a large number of 12v deep-cycle batteries connected together in order to run the inverter/motor combination for any length of time.

When it comes time to charging them back up using mains power, whatever power you put into the battery bank, you only get between 75% and 85% of the energy back; that is assuming that you have a 100% efficient charging system (which is impossible.)

It is really not practical to operate a large motor from an inverter. The only reason to do so would be if it were a dire emergency. If you really need to operate something during a power outage, you should consider getting a generator that can be powered by multiple fuel types.